The present invention concerns a turbine drive mechanism which is used to steer ultrasound signals generated by an ultrasound probe.
Catheter-based ultrasound probes are increasingly used in various medical applications, for example, in the imaging and diagnosis of vascular disease. Catheter-based ultrasound probes differ in beam configuration. For example, catheter-based ultrasound probes have been developed with a sector (wedge) beam configuration in which ultrasound beams are directed in a forward direction from the tip of the probe. Catheter-based ultrasound probes have been developed with a conical (funnel) beam configuration in which ultrasound beams are directed radially and at an angle forward. Also, catheter-based ultrasound probes have been developed in which ultrasound beams are directed in a 360 degree scan perpendicular to the long axis of the catheter. The catheter based system may scan an area by using a phased array of transducers, or by using a single mechanically rotated transducer. See, for example, Paul G. Yock, Eric L. Johnson and David T. Linker, Intravascular Ultrasound: Development and Clinical Potential, American Journal of Cardiac Imaging, Vol. 2, No. 3 (September), 1988, pp. 185-193.
In one prior art ultrasonic apparatus which uses mechanical movement to direct ultrasound beams outward from the apparatus, an ultrasonic transducer is carried by the distal end of a catheter adapted for insertion into a vessel. Either the transducer or another element is rotated and/or translated relative to the catheter to image different portions of the vessel. See U.S. Pat. No. 5,000,185, issued to Paul G. Yock, for METHOD FOR INTRAVASCULAR TWO-DIMENSIONAL ULTRASONOGRAPHY AND RECANALIZATION. In this prior art ultrasonic apparatus, torque for the rotation is provided via a motor connected through a torque cable to either the ultrasonic transducer or a reflective surface. This eliminates the bulk which results from inclusion of a phased array of piezoelectric transducers. The limited flexibility of a torque cable, however, restricts the range of uses of the ultrasonic apparatus.